Seal Of Faults And Their Controlling To Formation And Distribution Of Oil-gas Reservoirs In North And Middle Of Wuerxun Depression

Based on the research of structure and sedimentary background in working area, 11 faults (WU39,WU76,WU21,WU80,WU82,WU90,WU16,TB1,TB42,TB46,TB76) in north and middle of Wuerxun depression were selected for the research. The research on the development and distribution of these 11 faults were done by the change of fault distance strire distance, horicon faulted and dip angle based on seismic cross section and structure map, and the zonal distribution of faults had gotten. There are three main fault zones in the north of Wuerxun depression, south-north Huangqimiao, north-east-east Surennuoer and north-east Tongbomiao, and there are three main fault zones in the middle of Wuerxun depression, north-north-east Wuxi, nearly south-north middle and north-west middle-east fault zones. The two sets of fault systems are separated by T22 fault on cross section, upper and lower fault systerms, and the upper fault system developed on the lower fault system which controlled the upper fault system. The research on evolution history of these 11 faults in north and middle of Wuerxun depression were done based on structure evolution, and the fault active period had been gotten in the north and middle of Wuerxun depression, the first fault active period was from early k1t to end of k1n2 and the second fault active period was early k1y to early k2q. By using seepage experiment of oil-gas through fault zone and plastic deformation experiment of mudstone, the evaluation standards of fault seal were quantitatively determined, that's fault can seal oil vertically when the pressure on fault plane reaches 5MPa and mud content in fault zone reaches 50%, Bast on it, most faults has good vertical oil-gas seal quallty. Have no vertical unseal faults, little faults have betrter vertical oil-gas seal in K1d1.while most faults have good vertical oil-gas seal quallty. Have no vertical unseal faults, partly faults have poorer vertical oil-gas seal in K1n1.According SGR evaluation standards lateral seal of faults were studied. Most faults have good and poor lateral seal, lateral unseal faults distribute dispersely in k1n2 , most faults have poorer lateral seal even unsealed in k1n1. From development history of faults, most of the vertical seal of faults were formed at at early k2q.seal gradually increases and suitbale for oil-gas to accumulate and storage. From relationship between the distribution and period evolution of faults seal and the oil-gas distribution and expulsion hydrocarbon history of source rock, it is the faults in north and middle of Wuerxun depression that play an important role in controlling formation of oil-gas reservoirs and oil-gas distribution, that's the fault active in late k1y made oil-gas can transport to k1n2 formation. The good seal in k1d1 made oil-gas to accumulate in k1n2, and so the good lateral seal in k1n2 provide effective trap for oil-gas to accumulate.